Every internal combustion engine includes at least one intake valve to permit the air/fuel mixture to enter the cylinder and at least one exhaust valve to allow the burned exhaust gases to escape. The intake and exhaust valves, along with a cylinder head gasket, must also seal a combustion chamber.
Conventional internal combustion engines have a plurality of intake and exhaust valves, generally in a one-to-one relationship. Each valve comprises a head and an integral stem reciprocally mounted in a valve guide. Those skilled in the art will appreciate that there must be some oil flow along the stem in order to lubricate the latter as it reciprocates within the guide. As wear occurs in the valve guide and valve stem interface, oil flow will increase, causing excessive oil consumption and the formation of carbon deposits within the combustion chamber.
In order to reduce oil consumption and prevent carbon deposits, as well as to maintain engine performance, various designs have been developed to control or meter the oil flow between the stem and guide members. To the extent that relatively severe operating conditions occur in the exhaust and intake valve areas, much effort has been directed to geometries of valve sealing media.
In short, it is desirable to develop a method and a geometry that enhances the metering of oil between the valve stem and the valve guide, reduces manufacturing effort, and is easy to install.